 //导出页面为PDF格式
 import html2Canvas from 'html2canvas'
 import JsPDF from 'jspdf'
 export default {
    install(Vue, options) {
         Vue.prototype.getPdf = function (dom, title) {
             var title = title
             var c = document.createElement("canvas")
             var opts = {
                scale: 3,
                canvas: c,
                logging: true,
                width: document.querySelector(dom).offsetWidth,
                height: document.querySelector(dom).offsetHeight
             };
            c.width = document.querySelector(dom).width * 3
            c.height = document.querySelector(dom).height * 3
            c.getContext("2d").scale(3, 3);
            html2Canvas(document.querySelector(dom), opts).then(function (canvas) {
                     let contentWidth = canvas.width
                     let contentHeight = canvas.height
                     let pageHeight = contentWidth / 592.28 * 841.89
                     let leftHeight = contentHeight
                     let position = 0
                     let imgWidth = 595.28
                     let imgHeight = 592.28 / contentWidth * contentHeight
                     let pageData = canvas.toDataURL('image/jpeg', 1.0)
                     let PDF = new JsPDF('', 'pt', 'a4')
                     if (leftHeight < pageHeight) {
                        PDF.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight)
                     } else {
                         while (leftHeight > 0) {
                            PDF.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
                            leftHeight -= pageHeight
                            position -= 841.89
                             if (leftHeight > 0) {
                                PDF.addPage()
                             }

                         }
                     }
                    PDF.save(title + '.pdf')
                 })
         }
     }
 }
